Method for finishing internal gears



Hm 29 E935. R. s. DRUMMOND METHOD FOR FINISHING INTERNAL GERS Filed July 3o, 19:52 2 sheets-sheet 1 .13am 29, i935., R. s. DRUMMOND METHOD FOR FINISHING INTERNAL GEARS Filed July 30, 1932 2 Sheets-Sheet 2 Um Mw/jaw vb MM50 www@ Cil

Patented Jan. 29, i935 STATES PATENT OFFICE METHOD FOR FINISHING INTERNAL GEARS Application July 30, 1932, Serial No. 626,769

8 Claims. (Cl. 29-90) The invention relates to machines for finishing gears and it is the object of the present invention to obtain a construction for nishing internal gears and pinions for intermeshing with the same having teeth either parallel to or at an angle to the axis of rotation. To this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Figure 1 is a perspective view of the machine;

Figure 2 is an enlarged perspective view of an internal gear and its finishing pinion in intermeshing relation;

Figure 3 is a longitudinal section in the plane of the axis of the work spindle;

Figure 4 is a horizontal section through the internal gear showing the finishing pinion in engagement therewith; l,

Figure 5 is an end elevation of Figure 4.

Heretofore external gears have been finished by running same in mesh 'with a finishing tool in the form of a mating gear having conjugate teeth, the axes of the two gears being non-intersecting, having no common plane and being at a limited angle to each other (see my co-pending applications, Serial No. 604,575, filed April 11, 1932 and Serial No. 547,704, filed June 29, 1931). The finishing may be effected either through lapping, cutting, or burnishing, but in each case the relation of the work andthe finishing tool will be the same. It is the object of the present invention to finish internal gear wheels and pinions for the same by a similar action which is accomplished as follows: A is the internal gear wheel to be finished having its teeth at any desired helical angle. B is the finishing tool which is in the form of a pinion having teeth conjugate to the teeth of the internal gear wheel A but at a different helical angle so that when said gear and pinion are in intermeshing relation their axes will stand at an angle to each other. This angular dierence is limited to fall within 3 and 30 and consequently the gears when running in intermeshing relation will have progressive sliding contact with each other in a direction obliquely across the face of the tool. If the work gear is reciprocated axially thereof this rubbing contact will be distributed over the full width of the gear:

As shown in Figure 1, the machine is provided with a frame C having mounted thereon the head stock D for the spindle of the finishing tool B. The work A is mounted on a tail stock E but this tail stock is capable of angular adjustment. Preferably this is accomplished by mounting the tail stock upon a column F which is adjustable around a segmental bed G on the frame C. The tail stock E is directly connected to a cross head H which is slidable upon horizontal ways I on a second head J vertically adjustable on the column F.

The internal gear wheel A to be finished is mounted i'n a suitable chuck K journaled on the spindle L in the tail stock, and a split collet K adjustable in a tapering socket in the chuck K by means of a screw K2 serves to clamp the ring gear in position. Adjustment for proper helix angle is accomplished by moving the column F around on the segmental ways G and by vertically adjusting the head J the gear A is intermeshed with the finishing tool B. Rotary mo tion is then imparted to the tool B by suitable means not shown which will run this tool in mesh with the internal gear wheel. If the operation is lapping, suitable abrasive material is introduced between the teeth of the intermeshing gears, or if on the other hand the operation is cut-y ting, the tool is properly fashioned for this purpose. Pressure contact is obtained either by cramping the tool in mesh with the gear, 0r as shown in Figure 1, by providing a power tail stock in which the intermeshing gears M con' neet the spindle L to a hydraulic brake (not shown) within thev tail stock. Axial motion is also imparted to the work gear during the finishing operation, thereby spreading the action over the entire surface of the gear. This axial movement can be obtained by reciprocating the head H upon the horizontal ways I'by any suitable mechanism (not shown) As shown in Figure 2, the tool B is a helical pinion which is in mesh with a straight tooth internal gear wheel A. However, in place of a straight tooth gear, a gear of any desired helical angle may be finished in the same manner by a tool of the proper helical angle. It is essential however, that the axis of the tool and the axis of the gear should be atan angle to each other within the limits of 3 and 30.

As shown in Figure 4, instead of using the tool for lapping the gear, the tool is formed of hard material and is provided with a groove B' in the teeth thereof which extends upon opposite sides of the theoretical point of contact O between the tool and the work gear. This will produce a cutting action when the gears are run in intermeshing relation and in pressure contact with each other, but this cutting tool fonnslthe subject matter of my application for patent Serial No.

626,768, filed July 30, 1932 and will not therefore be further described in detail.

In place of finishing an internal gear with an exterior gear or pinion, the reverse operation may be performed by using the internal gear as the tool and finishing therewith an external gear or pinion. In each case the interaction will be the same'but by imparting the axial reciprocation to the work the finishing operation will be spread over the entire width of the teeth.

What I claim as my invention is:

1. The method of finishing internal gears comprising running the internal gear to be nished in mesh with a finishing tool having external conjugate teeth, the axes of said gear and tool being crossed at an angle less than30 and lying in no common plane and axially feeding said internal gear to thereby finish the entire tooth surface of said gear.

2. The method of finishing external gears comprising running the external gear to be finished in mesh with a finishing tool having internal conjugate teeth, the axes of said gear and tool being crossed at an angle less than '30 and lying in no common plane and axially feeding said external gear to thereby finish the entire tooth surface of said gear.

3. The method of finishing a straight tooth internal gear comprising running the straight tooth internal gear in mesh with a finishing tool having external helical conjugate teeth and a helical angle less than 30, the axes of said gear and tool being crossed at an angle less than 30 and lying in no common plane and axially reciprocating said internal gear to thereby finish the entire tooth surface of said gear.

4. The method of finishing gears comprising selecting a finishing tool having teeth conjugate to the teeth of the gear to be finished and adapted to have an internal-external meshing engagement with said gear, the helical angleI of said finishing tool differing yfrom the helical angle of said gear such that during said intermeshing engagement the axis of said gear is crossed at an angle less than 30 with the axis of said finishing tool, mounting said gear and said finishing tool on rotatable members having their axes crossed at said angle less than 30, rotating one of said members thereby driving the other member through the intermeshing engagement of said gear and tool, applying pressure to said driven member to obtain pressure c ontact between `the teeth of said gear and tool and feeding one of said members relative to the other in the direction of the axis of said gear thereby finishing the entire tooth surface vof said gear.

5. The method of finishing gears comprising selecting a finishing tool having teeth conjugate to the teeth of the gear to be finished and adapted to have an internal-external meshing engagement with said gear, thehelical angle of said finishing tool differing from the helical angle of said gear such that during said intermeshing engagement the axis of said gear is crossed at an angle less than 30 with the axis of said finishing tool, mounting said gear and said finishing tool on rotatable members having their axes crossed at said angle less than 30, rotating one of said members thereby driving the other member through the intermeshing engagement of said gear and tool, applying resistance to the rotation of said driven member to obtain pressure contact between the teeth of said gear and tool and feeding one of said members relative to the other in the direction of the axis of said gear thereby finishing the entire tooth surface of said gear.

6. The method of finishing gears comprising selecting a nishing tool having teeth conjugate to the teeth of the gear to be finished and adapted to have an internal-external meshing engagement with said gear, the helical angle of said finishing tool differing from the helical angle of said gear such that during said intermeshing engagement the axis of said gear is crossed at an angle less than 30 with the axis of said finishing tool, mounting said gear and said finishing tool on rotatable members having their axes crossed at said angle less than 30, rotating one of said members `thereby driving the other member through the intermeshing engagement of said gear and tool, applying a predetermined pressure on one of said members toward the axis of the other member thereby obtaining pressure contact between the teeth of said gear and tool and feeding one of said members relative to the other in the direction of the axis of said gear thereby finishing the entire tooth surface of said gear.

7. The method of lapping gears comprising selecting a finishing lap having teeth conjugate to the teeth of the gear to be finished and adapted to have an internal-external meshing engagement with said gear, the helical angle of said finishing lap differing from the helical angle of said gear such that during said intermeshing engagement the axis of said gear is crossed at an angle less than 30 with the axis of said finishing tool, mounting said gear and said finishing lap on rotatable members having their axes crossed at said angle less than 30, applying abrasive to the tooth surfaces of said lap and gear, rotating one of said members thereby driving the other member through the intermeshing engagement of said gear and lap, applying pressure to said driven member to obtain pressure contact between the teeth of said gear and lap and axially reciprocating one of said members relative to the other in the direction of the axis of said gear thereby finishing the entire tooth surface of said gear.

8. The method of lapping an internal gear comprising selecting a finishing lap, having external teeth conjugate to the internal teeth of the gear to be finished and adapted to mesh therewith, the helical angle of said finishing lap difiering from the helical angle of said internal gear such'fthat when said gear and lap are in intermeshing engagement the yaxis, of said gear is crossed at an angle of less than 30 with the axis of said finishing lap, mounting said gear and said lap on rotatable members having their axes crossed at said angle less than 30, applying abrasive to the teeth of said gear and lap, rotating said external lap thereby driving said internal gear, applying resistance to rotationof said driven internal gear thereby obtaining pressure contact between the teeth of said gear and lap and reciprocating said internal gear relative to said lap in the direction of the axis of said gear thereby finishing the entire tooth surface of said gear. l

ROBERT S. DRUMMOND. 

